app_keyprefetch: Add key to inkeys if loaded but not in config.

Back port a workaround present in res_phreaknet to app_keyprefetch
to handle an edge case where the inkey is already loaded by res_crypto,
but is not present in the iax.conf section's inkeys setting, for
whatever reason. Otherwise, we would load the public key and it would
never get used for matching on incoming calls (short of some manual
effort to resync by purging keys).

Author: InterLinked1

apps/app_keyprefetch.c

@@ -141,6 +141,7 @@ static int fetch_exec(struct ast_channel *chan, const char *data)
 	int reload = 1, newkey = 1, needreload = 0;
 	struct ast_key *inkey;
 	char *filepath;
+	struct ast_config *cfg = NULL;
 
 	AST_DECLARE_APP_ARGS(args,
 		AST_APP_ARG(cat);
@@ -306,8 +307,38 @@ static int fetch_exec(struct ast_channel *chan, const char *data)
 		}
 		ast_free(tmp_filename);
 	}
+	if (!newkey) {
+		/* Check if the key is loaded but isn't present in the inkeys in iax.conf.
+		 * If this happens for some reason, we still need to add it. */
+		struct ast_flags config_flags = { CONFIG_FLAG_WITHCOMMENTS | CONFIG_FLAG_NOCACHE };
+		char *sfn = "iax.conf";
+		if ((cfg = ast_config_load2(sfn, "app_keyprefetch", config_flags))) {
+			const char *currentinkeys = ast_variable_retrieve(cfg, args.cat, "inkeys");
+			if (currentinkeys) {
+				char search_str[256];
+				size_t curlen = strlen(currentinkeys);
+				/* Surround existing key list with : before/after to ensure we can match even if it's the first or last key name,
+				 * and to avoid false positive on a key name with a partial name match. */
+				char *haystack = ast_alloca(curlen + 3); /* 2 colons and NUL */
+				*haystack = ':'; /* Before */
+				strcpy(haystack + 1, currentinkeys); /* Safe */
+				haystack[curlen + 1] = ':'; /* After */
+				haystack[curlen + 2] = '\0';
+				snprintf(search_str, sizeof(search_str), ":%s:", args.keyname);
+				if (!strstr(haystack, search_str)) {
+					ast_debug(1, "Key '%s' is loaded but not an inkey of %s currently (%s), need to add it\n", args.keyname, args.cat, haystack);
+					newkey = 1;
+				}
+			}
+		}
+		if (!newkey) {
+			/* If we don't need the config anymore, we can destroy it now.
+			 * If we set newkey true above, then we keep using it below without reopening. */
+			ast_config_destroy(cfg);
+			cfg = NULL;
+		}
+	}
 	if (newkey) { /* add the new key we just got to the list of inkeys allowed */
-		struct ast_config *cfg;
 		struct ast_category *category = NULL;
 		struct ast_flags config_flags = { CONFIG_FLAG_WITHCOMMENTS | CONFIG_FLAG_NOCACHE };
 		char *sfn = "iax.conf", *dfn = "iax.conf";
@@ -317,12 +348,14 @@ static int fetch_exec(struct ast_channel *chan, const char *data)
 		ast_debug(1, "Got a new key, '%s', adding to inkeys\n", args.keyname);
 		pbx_builtin_setvar_helper(chan, "KEYPREFETCHSTATUS", "NEW");
 
-		if (!(cfg = ast_config_load2(sfn, "app_keyprefetch", config_flags))) {
-			ast_log(LOG_WARNING, "Config file not found: %s\n", sfn);
-			goto done;
-		} else if (cfg == CONFIG_STATUS_FILEINVALID) {
-			ast_log(LOG_WARNING, "Config file has invalid format: %s\n", sfn);
-			goto cfgcleanup;
+		if (!cfg) { /* Open config, if not already open from the !newkey branch above */
+			if (!(cfg = ast_config_load2(sfn, "app_keyprefetch", config_flags))) {
+				ast_log(LOG_WARNING, "Config file not found: %s\n", sfn);
+				goto done;
+			} else if (cfg == CONFIG_STATUS_FILEINVALID) {
+				ast_log(LOG_WARNING, "Config file has invalid format: %s\n", sfn);
+				goto cfgcleanup;
+			}
 		}
 
 		while ((category = ast_category_browse_filtered(cfg, cat, category, NULL))) {